Devices for electronically recording sound messages and for selectively playing them back are known in several technical fields. Such devices have been used, for example, in music instruction, language education, voice-mail systems, and telephone answering machines. The fields of principal interest contemplated for the present invention are training of retarded children and rehabilitation of handicapped persons.
There is a need for a lightweight, portable sound-recording and playback device having multiple, selectable message channels for use in training therapy for retarded children and for use by severely handicapped persons unable to speak and capable of only slight motor activity. Many retarded children are also impaired in motor ability, so that they fall into both of the foregoing categories.
Retarded children often have severe developmental delays in language skills. In some cases these children are nonverbal. They have minimal receptive language skill, and have virtually no expressive language skill. These children may be mobile and interact knowledgeably with their environment, and show preferences for certain activities or objects, among which they are capable of discriminating, but their ability to express their desires is limited to generalized demonstrations, such as clapping or crying. Conveyance of expressive language skills to the severely retarded is considered a major educational goal.
A typical approach to teaching expressive language skills uses photographs of objects from the child's environment. The photographs are typically of favorite toys or foods. In a preliminary stage of training, the child is shown such a photograph. When the child touches the picture, the actual object is handed to the child as a reward. In this stage of training, the child is positively reinforced for the motor act of touching the picture. In a second stage of training, two pictures are presented simultaneously and the child is encouraged to discriminate between them by selecting one picture. Here, pictures of highly desirable objects may be paired with pictures of less desired or less interesting objects. Each time the child chooses a picture, the depicted object is given to the child. The purpose is to cause the child to associate appropriate picture choices with obtaining the more desirable objects. Establishment of this association represents successful conveyance of a rudimentary, but flexible, expressive language skill. Picture selection provides a critical communication link between a retarded person and his caretakers. It also lays the conceptual groundwork for more advanced communication skills.
So-called "speech feedback" is considered to be a valuable adjunct to the above educational paradigm. See, e.g., L. J. Burkhart, Using Computers and Speech Synthesis to Facilitate Communicative Interaction With Young and/or Severely Handicapped Children (1987). Speech feedback utilizes a recorded voice stating the name or meaning of the picture, each time that the child touches the picture. This feedback captures the child's attention, a key element in teaching severely retarded children. Further, the recorded message taps into the child's receptive language capacity via an auditory channel supplementing the visual impression that the picture creates. Because the human brain has different sensory pathways to language centers, use of two independent sensory modalities enhances communication by facilitating semantic comprehension. Thus, combining the auditory modality with the visual one increases the likelihood of transferring the desired lexical meaning to the brain's language centers. See A. S. Gilinsky, Mind and Brain: Principles of Neuropsychology (1984).
As B. F. Skinner demonstrated, learning depends on appropriate reinforcement. Learning to discriminate occurs only when a child has the opportunity to make a "wrong" selection and thus receive the less-desirable object, as well as the opportunity to make a "correct" selection. Accordingly, it is necessary to have at least two pictures and two recorded messages, each message being uniquely associated with a different one of the two pictures, for the child to learn to discriminate. Additionally, it is possible to unambiguously quantify progress in training a retarded child by measuring performance in a choice task. In addition, the messages must be changed each time that the pictures are changed. This requires either a large library of prerecorded messages or a quick and easy mechanism for recording new messages. Ideally, training should occur in a variety of daily environments, not just a speech-therapy laboratory. The device, if any, used for training should therefore be portable so that it can also be used away from formal therapy settings, for example, at home or in playgrounds.
Such a device, if available, could also be used as an aid in teaching very young, unretarded children how to speak and to discriminate. Similar considerations are applicable in that context to those discussed above.
Presently available devices in this field are not well adapted to the foregoing use by handicapped persons and retarded or very young children. Devices using moving magnetic tape transports for sound-recording and playback require electric motors. Motors are relatively heavy and consume relatively large amounts of power, making devices containing them neither lightweight nor conveniently portable. Further, moving tape devices are limited to only one message per tape unless special equipment is used to position the tape automatically for each message. Such equipment tends to be costly and/or bulky. Moreover, a tape-positioning device introduces time delays between the activation of the device and message playback, which interfers with the teaching/learning reinforcement function and is also simply inconvenient. Typical portable electronic-storage sound-recording and playback devices either consume significant amounts of battery power between message playbacks or use complex circuitry to regulate power consumption.
Accordingly, such devices have not been available in inexpensive and portable form. There are excellent stand-alone multi-channel (4 to 16 channel) record/playback devices which are now used for voice feedback in language training. But these commercial devices are more elaborate than necessary for two-choice picture training; some are not portable; and they retail for approximately $400 to $1600, making them impractical for individuals and most public institutions. It is believed that no practical commercial device now exists for appropriate two-choice picture training of retarded children, for example, for use at home or playground.